The location service (LCS) of a mobile communications network is to obtain the location of a target user's equipment (UE) with location techniques, wherein the target UE refers to a user terminal which is to be positioned in a mobile communications network and the location may be geographical information expressed in latitude and longitude or location data with reference to local streets. The location obtained by a mobile communications network may be offered to the target UE for the target UE's self-locating, or to the communications network itself for area-specific charging or operational maintenance, or to other application clients, for instance, agencies or individual, requesting the location of the target UE for value-added services. Therefore, the location service has wide applications in such fields as emergency rescue, vehicle navigation and intelligent traffic systems, job dispatch and team management, mobile-yellow-page query, and enhancement of network performance. In the 3rd Generation Partner Project (3GPP), specifications on LCS as well as the operational mode, structure, state description, and message flow for implementing the LCS have been described.
FIG. 1 is a schematic diagram illustrating the logical structure for implementing the LCS. As shown in FIG. 1, a requestor 101 requests the location of a target UE 103 from a network 102 which contains an LCS system. The network 102 makes a validity authentication of the requestor 101 to check whether the target UE 103 permits providing the location of the target UE 103 for the requestor 101. If the requestor 101 passes the validity authentication by the network 102, the network 102 will accept the request initiated by the requestor 101 for the location of the target UE 103, locate the target UE 103, and provide the requestor 101 with the positioning result of the target UE 103; otherwise, the network 102 will reject the request initiated by the requestor 101 for the location of the target UE 103. For the purpose of description, the network containing an LCS system is hereinafter named an LCS system for short. Here, the request for location originated by the target UE may be a Location Service Invoke sent to a Mobile Switch Center (MSC)/MSC Server or an LCS MO-LR Invoke sent to a Serving General Packet Radio Service (GPRS) Support Node (SGSN); the requestor may be an LCS Client, a group of LCS Clients, the target UE itself, or any other terminal that is able to process the location information of the target UE.
Logical functionality for implementing the location service in an LCS system include a Gateway Mobile Location Center (GMLC), a Subscriber Data Storage Server, such as a Home Location Register/Home Subscriber Server (HLR/HSS), a Core Network (CN), and a Radio Access Network (RAN). The GMLC may further include a Requesting GMLC (R-GMLC), a Home GMLC (H-GMLC), and a Visited GMLC (V-GMLC). The R-GMLC is the GMLC for receiving the request for location of the target UE initiated by a requestor, The H-GMLC refers to the GMLC which the target UE belongs to, and the V-GMLC refers to the GMLC which currently serves the target UE, that is, the GMLC which is associated with the serving node of the target UE currently. The R-GMLC, the H-GMLC, and the V-GMLC may be integrated in the same physical entity, or may be in separate physical entities.
So far, a procedure of a Mobile Originating Location Request (MO-LR) has been defined in the 3GPP specifications. The MO-LR is a request initiated by a target UE for its own location from an LCS system. After positioning the target UE, the LCS system will return a positioning result to the target UE. Furthermore, based on the request of the target UE, the LCS system may provide the positioning result of the target UE for an external requestor. The requestor herein refers to an LCS client or other application client that is able to handle the location information of the target UE.
FIG. 2 is a flowchart for processing an MO-LR in the prior art. As shown in FIG. 2, the processing of an MO-LR comprises the steps of:
Step 201: A target UE sends a service request carrying the identity of the target UE to the CN via RAN, requesting to establish a radio signaling connection with an LCS system. Then the LCS system may initiate a procedure of authentication and ciphering for the target UE according to the identity of the target UE. If the target UE has been authenticated by the network containing the LCS system, continue with step 202; otherwise, reject the service request for establishing a radio signaling connection initiated by the target UE and terminate the current processing of the MO-LR.
Steps 202: The target UE sends a Location Service Invoke including an identity of the target UE to the CN via RAN, requesting the LCS system to position the target UE and return the positioning result to the target UE. The Location Service Invoke may further carry an identity of a requestor, requesting the LCS system to provide the location information of the target UE for the requestor. The Location Service Invoke may further carry a GMLC address designated by the target UE, requesting the CN to provide the location information of the target UE for the requestor via the GMLC corresponding to the GMLC address. if the Location Service Invoke carries no GMLC address, The CN will assign a GMLC for the Location Service Invoke according to the assigned GMLC address saved in the CN and provide the requestor with the location information of the target UE via the GMLC assigned by the CN. Wherein, the GMLC assigned by the CN is called V-GMLC.
Steps 203˜205: After receiving the Location Service Invoke, the CN sends a Location Request carrying the identity of the target UE to the RAN. Upon receiving the Location Request, the RAN will position the target UE according to the identity of the target UE. If the RAN succeeds in positioning the target UE, it returns a Location Report including the location information of the target UE to the CN. After the CN receives the Location Report carrying the location information of the target UE, it determines whether the Location Service Invoke initiated by the target UE carries a GMLC address or not, and if yes, The CN will continue to decide whether the CN itself can directly access the GMLC which corresponds with the GMLC address. If the CN can directly access the GMLC, it will send a Subscriber Location Report of the target UE directly which carries the identity and location information of the target UE to the GMLC. Wherein the interaction between the V-GMLC and the GMLC as shown in FIG. 2, i.e., Steps 207 and 210, may be skipped; if the CN can not access the GMLC directly, it will assign a V-GMLC that can directly be accessed by itself, and send a Subscriber Location Report to the V-GMLC which includes the identity and location information of the target UE, the identity of the requestor, and the GMLC address carried in the Location Service Invoke, and then continue with Step 206. If the Location Service Invoke initiated by the target UE carries no GMLC address, the CN will assign a V-GMLC that can be directly accessed by the CN, send a Subscriber Location Report of the target UE to the V-GMLC which carries the target UE's identity, the location information of the target UE, and the requestor's identity, and then continue with Step 206. If the RAN fails to position the target UE, it will return a Location Report carrying a value of error cause to the CN, and go directly to Step 212, i.e., the CN sends an LCS MO-LR Return Result carrying the value of error causes to the target UE via RAN.
Step 206: After receiving the Location Report of the target UE, the V-GMLC decides whether it carries the address of the GMLC, and if it does, then go to Step 207; otherwise, the V-GMLC will determine whether it is able to access the requestor directly according to the identity of the requestor. If the V-GMLC can access the director directly, it will directly send a Location Information of the target UE which carries the identity and location information of the target UE to the requestor, wherein the interaction between the V-GMLC and the GMLC, i.e., Step 207 and Step 210, may be skipped; otherwise, the V-GMLC will assign a GMLC that can access the requestor according to the identity of the requestor, and then continue with Step 207.
Step 207: Based on the GMLC address, the V-GMLC sends an MO-LR Location Information which carries the identity of the target UE, the location information of the target UE, and the identity of the requestor to the GMLC. In LCS, an MO-LR Location Information sent to a GMLC, a Mobile Application Part (MAP) Subscriber Location Report or Subscriber Location Report sent to a V-GMLC, a Location Information sent to the requestor may be called a location report of the target UE in a general designation.
Step 208: After receiving the MO-LR Location Information of the target UE, the GMLC sends a Location Information of the target UE which carries the identity and location information of the target UE to the requestor according to the identity of the requestor.
Step 209: After receiving the Location Information of the target UE, according to the service requirement, the requestor makes a corresponding process of the target UE's location information and then returns a Location Information Ack of the target UE to the GMLC. If the Location Information of the target UE received by the requestor is from the V-GMLC, the requestor will directly return the Location Information Ack of the target UE to the V-GMLC.
Step 210: Upon receiving the Location Information Ack of the target UE, the GMLC returns an MO-LR Location Information Ack of the target UE to the V-GMLC. If the MO-LR Location Information received by the GMLC comes from the CN, the GMLC directly returns the CN a Subscriber Location Report Ack of the target UE.
Step 211: After receiving the MO-LR Location Information Ack of the target UE, the V-GMLC returns the CN a Subscriber Location Report Ack of the target UE.
Step 212: After receiving the Subscriber Location Report Ack, the CN sends the target UE an LCS MO-LR Return Result carrying the location information of the target UE via RAN, which informs the target UE that its location information has been provided for the appropriate requestor and notifies the target UE the processing result of the target UE's location information for the requestor.
If the requestor is able to process the location information of the target UE based on the service requirement, the Location Information Ack of the target UE that the requestor returns to the LCS system will include a success flag, and correspondingly, the LCS MO-LR Return Result which the LCS system sends to the target UE will carry a success flag and further include the requestor's process result of the target UE's location information; if the requestor cannot process the location information of the target UE according to the service requirement, the Location Information Ack of the target UE returned by the requestor to the LCS system will carry a failure flag, and correspondingly, the LCS MO-LR Return Result sent by the LCS system to the target UE will include a failure flag and may further carry a value of error cause. Here, the location information is for describing the location of the target UE. The location information transmitted among the entities in network side, e.g., the RAN, GMCL, V-GMLC, and CN, may not be processable for terminals e.g., requestors and UE. So when a network entity sends the location information of the target UE to a requestor, the entity may first make a transformation for the received location information. Thus the received location information is transformed into another form of location information which can be processed by the requestor, and the entity can subsequently send the transformed location information to the requestor.
As seen from the MO-LR procedure defined by the 3GPP specifications said above, if the target UE requests its own location to an LCS system and asks the LCS system to provide the location information of the target UE for a requestor, after positioning the target UE and obtaining the location estimate of the target UE, the LCS system will provide the location information of the target UE for the requestor according to the location estimate. As providing the requestor with the location information of the target UE, the LCS system simultaneously provides a real identity of the target UE to the requestor. The real identity is a kind of identity that is assigned to the target UE in a unified way by the mobile communications network and is able to uniquely identify the target UE, e.g., the Mobile Station International ISDN Number (MSISDN) or the International Mobile Subscriber Identity (IMSI). In practice, when a target UE requests an LCS system that provides a requestor with the location information of the target UE, for the sake of security and privacy, the target UE may hope the real identity of itself be concealed.